Steering mechanism



Dc. 12, 193,3.` w. A. EATON ET AL STEERING MECHANISM Original Filed May 3, 1932 ...ll` A ,E bd.

...W-M. m

Patented Dee;

- PAFTfl-:NT carica '1,938,745l streamNdMechanism Wilfred A. Eaton and Stephen Vorech, Pittsburgh, Pa., assignors to Bendix-Westinghouse Automotive Air Brake Company, Pittsburgh,

. Pa., a corporation of Delaware.

Original application May 3, 1932, Serial No.

609,018. Divided and this application July 21, 1933. Serial No. 681,583 f 8 Claims.

steer motor vehicles of the larger type, such as' trucks or busses, with a, minimum amount of effort and at the same time have complete control only and is not designed as a definition of 'the of the steering of such vehicles as heretofore.

Still another object is to provide a novel power steering mechanism for motor vehicles so constituted asto enable manual control of the steering operation to effect a combined manual and power steering operation. Y

A further object is to provide in a mechanism of the above character, a novel arrangement of -parts whereby manually controlled power operation of the steering apparatus will include a feel 4or reaction which will be reflected in the manually 'controlled member in order to simulate as closely as possible the feel or resistance heretofore encountered during manual steering.

A still further object is to provide in a poweroperated steering mechanism for motor vehicles, a novel, simple and compact arrangement of parts so constituted as to be relatively light in weight and capable of ready installation without the necessity of completely rebuilding manually-operated steering mechanisms now in common use.

The above and othernovel features of the invention will appear more fully hereinafter from the following detailed description when taken in connection with the accompanying drawing, wherein one embodiment of theinvention is illustrated. Itis to be expressly understood, however, that the drawing is for purposes of illustration limits of the invention, reference being hadV for this purpose to the appended claims.

.apparatus constructed in accordance with'the (C1. iso-79.2)

Referring to the drawing, the invention dis-v closed therein includes a manually-operable steer ing shaft 40B having a cam or'worm 40- adapted y to mesh with a suitable segmental gear member 41 rotatably mounted on the vehicle frame in any 60 suitable manner and securely attached to .one end of a lever 42. The vother end of the last-mentioned lever is suitably connected to one end of a lever 43 by links 44 and 45, the opposite end of lever 43 being formed with a hub portion 46, Fig. 6 2, surrounding but spaced from a stub shaft 47 suitably secured to the vehicle frame. As shown,` the lever 43 is pivotally mounted in ermediate its ends by means of a pivotpin or bo t 48 to a pitman arm or lever 49, one end of which is rotat- 70 ably mounted upon the stub shaft 47 by means of a bushing 50. As shown inFigs. 1 and 2, the lower end of the pitman arm or lever 49 is secured to a drag link and steering connections of suitable design,v it ,being pointed out-that pivotal Imovement of arm 49 about the stub shaft 47v will eiect steering of the dirigible wheels of the vehicle accordingto the direction of rotation of the cam 49.

Means are provided for operating the arm 49 by power, and preferably such power means are controlled by operation of the steering cam 40. As shown, such power means are constituted by power cylinders 50 and 51 hav g pistons 52 and 53 respectively, which are interconnected by means of rods 54 and 55, the means for interconnectingv such rods comprising a/suitable coupling member 57 which is secured to the pitman arm 49 bymeans of a pin 56. Any suitable fluid under pressure, such as air, is adapted to be conducted to the' power cylinders 50 and 51' through ducts 25 and valve mechanisms 58 and 59, such valve mechanisms being provided with operating rods 60 and 61 which `are respectively connected with collars 62 and 63 rotatably mounted upon the hub portion 46 of lever 43, Fig. 2.

Referring more particularly to Fig. 3, the valve mechanisms 58 and 59 each includes a casing 28 having intake and exhaust valves 29 yand 30 secured together and reciprocatingly mounted therein, there being provided resilient means 31 for normally maintaining the valve 29 upon a seat 32 secured to the casing. The exhaust valve 30, as shown, is normally' spaced from its seat 33 formed in the head of a reciprocating piston member '34, this` last-named member having a bore 35 formed therein which normally establishes communication between oniside of the fluid motor and the atmosphere through 36 as- -lg I turned in such a direction as to effect a counterclockwise movement of gear segment 41 with respect to its'pivotal mounting on the vehicle frame, it will be readily observed that links 44 and 45 .will be moved to the right effecting a counterclockwise movement of lever 43`about its pivot 48 which latter, it will be appreciated,

momentarily remains stationary, since the same is connected through `arm 49 to the dirigible viewed in Fig. 1, taking up the lost motion exwheels of the vehicle and to the pistons 51 and 52 of the power cylinders.' Upon the counterclockwise movement pf lever '43, itwill be readilyobservedithat the hub portion 46 of said;v lever, together with collars 62 and 63 rotatably mounted thereon, will be moved to the left, as

isting betweenhub portion 46 and stub shaft 47, such movement'ei'fecting operation of the valve 58 to admit fluid under pressure to power cylinder 50 which will cause rod 54'to move to the right in order to effect power operation of the pitman arm 49. It will also be readily ob- -s'erved that the valve mechanism 58 will be rendered inoperative by counterclockwise movement of lever 49 about the stub .shaft l47 by reason of the interconnection between the pitman larm 49 and lever 43 at 48, such connection effecting a movement of hub portion 46 to the right, it being appreciated that the lower end of lever 43 'secured to the links 44 and 45 will remain substantially stationary in view of the self-locking nature of the cam 40. It will be understood that continued rotation of the cam 40 will, after the lost motion between hub 48 and the stub shaft 47 has been taken up to operate the selected fluid motor, enable the manual effort of the operator to be added to the power operation of the steering mechanism.

Preferably, the springs 37 of the valve mechanisms are so constructed as to readily yield during the usual operation of the steering mechanism in order to permit the functioning of the power apparatus. However, under certain circumstances it may be desirable to steering the vehicle manually, in the usual manner, and to permit the power apparatus to become'operable only when a predetermined resistance to steering is encountered, such as for example, during travel in sandy or muddy roads, such an operation obviously conserving the supply of compressed air required to be carried `by the vehicle. In such event it is only necessary to construct the springs 3'7 in such a manner that they will oppose the tendency of the valve operating rods 60 and 61 to com- 4press them, during operation. of the steering mechanism when only slight resistance tov steering is encountered, but will yield as soon as a predetermined resistance is reached, thereby permitting operation of the power apparatus.

` It will be appreciated from the above that the construction of the parts is such as to'enable a feel or resistance to steering to be reiiected in the steering shaft 40 in order to convey to the operator the usual reaction to steering encountered during normal operation of lsteering gears of the manually-operated, type, which reaction is highly desirable in steering mechanisms operated by power. For example, as soon as the lost motion existing between the hub portion 46 of the lever 43 and the stub shaft 47 has been taken up, considering movement'of the segment 41 in a clockwise direction, and air under pressure is being conveyedto the power cylinder 53, it will be obthus exerting a certain predetermined resistancev to the turning of the cam 40 when operated to effect a steering of the dirigible wheels of the vehicle. Thus. substantially simultaneously with tha-actuation of the steering shaft 40 by the operator to effect a movement of the upper end of lever 43 to the right, as viewed in Fig. 1, the operation ofthe valve mechanism will cause a reaction to be exerted which is conveyed to the operator through the steering shaft 40". Such an arrangement is extremely advantageous, as will be' appreciated ,.in that the usual'resistance lor reactionoffered to, steering may be readily noted by the operator.

There is thus provided bythe present invention a .power steering mechanism of relatively few parts,.so constituted as to be capable of ready installation upon motor vehicles with a minimum amount of rearrangement of the steering apparatus thereonf The provision of the lost motion in the steering operating linkage enables ready actuation of the valves controlling the flow of fluid under pressure to the power actuators and moreover provides a construction 5whereby the manual effort of theoperator mayjely supplement the power operation ofthelfsteering mechanism. The arrangement of these valves and of the power actuators, as above`desc1ibed,

is also ofsuch a nature as to enable a reaction or resistance tobe exerted upon the manuallyoperable steering shaft which is readily noticeable by theoperator when rotating such shaft, to

iis

the endthat the operator may more readily gauge the degree of steering as in steering mechanism of the manually-operable type.

While only one embodiment of the invention has been lillustrated and described, it is to be understood l that the invention is not limited thereto but may be capable of being employed in other forms as well understood by those skilled in the art. v Furthermore, the parts disclosed herein may be rearranged if desired," and certain of the parts may be used without others without departing from the spirit of the invention. Reference will therefore be had to the appended claims for a definition of the limits of the invention.

1. A motor vehicle power steering mechanism having a manually rotatable cam, a steering lever, a stationary stub shaft, a member operatively connected at one end with said cam and having a lost motion connection at its other end with said shaft, a second member operatively connected at one end with said steering lever and rotatably mounted at its other end on said shaft, means forvpivotally connecting each of said members together intermediate the ends thereof, a fiuid motor connected with said second member, and means dependent upon pivotal movement of said first named member with respect to said second member to take up said lost motion for controlling the operation of said motor.

2. In combination with a manually-rotatable steering shaft, a steering member, a fluid pressure motor operatively connected with said steering member, valve means for controlling said motor, and means for operatively connecting said shaft and steering member and for controlling said valve means to effect power operation or combined power and manual operation of said steering member comprising a lever operatively connected with said steering member and directly connected with said fluid motor, a valve control lever pivotally mounted intermediate i's ends to said first named lever,one end of saidvalve control lever being operatively connected with said manually-rotatable steering shaft independently of said first named lever, means for connecting the opposite end of said control lever to said valve means, and means for mounting said last named end to allow limited pivotal movement of the control lever with-respect to said first named lever to operate said valve means, one end of the rst named lever being fulcrumed on said mounting means.

3. In a power steering mechanism for the dirigible wheels of a motor vehicle, a manually operable steering member, a lever connected with said member and adapted to be oscillated thereby, a power operated steering arm connected to the dirigible wheels of the vehicle, a fluid pressure power means operatively connected with said steering arm, valve means for controlling said power means, and means for controlling said valve means comprising a valve control vlever pivotally mounted on said steering arm, a connection between said valve control lever and said first-named lever independent of said pivotal mounting, and a connection between one end of said valve control lever and saidvalve means..

4. In a motor vehicle power steering mechanism, an oscillatable lever adapted-to be manually oscillated in opposite directions for steering,

a stationary stub shaft spaced laterally from said lever, a pitman arm having one end thereof journalled on said shaft. a power device connected with said arm adjacent the other end thereof, a control means for said power device including a lever pivotally connected intermediate its ends to said arm, one end of said last-named lever `having an opening surrounding but normally spaced from said stub shaft, and means for connecting the other end of said last-named lever land the free end of said oscillatable lever.

5. A motor vehicle power steering mechanism having a `manually rotatable steering shaft, a drag link, a stationary stub shaft, a lever operatively-connected at one end with said steering shaft and'having a lost motion connection' at its other end with said stub shaft, a pitman arm operatively connected at one end with said drag link and rotatably mounted at its other end on said stub shaft, means for pivotally connecting said lever and arm together intermediate the end s thereof, a fluid motor having a movable element operatively connected with said arm between the connections thereof with said. lever and drag link, and valvular means dependent upon pivotal movement of said lever with respect to said arm to take up said lost motion for controlling the operation of said motor.

6. A motor vehicle power steering mechanism having a manually rotatable shaft, a stationary stub shaft, a steering lever having one end thereof journalled on said stub shaft, power means operatively connected to said steering lever, means for controlling said power means comprising a lever pivotally mounted intermediate the ends thereof on said steering lever and having a hub formed on one end surrounding but normally spaced'fror'n said stub shaft, and means for connecting the other end of said lever to said manually rotatableshaft independently of said pivotal mounting.

7. A motor vehicle power steering mechanism having a manually rotatable steering shaft, a drag link, means including a pair of pivotally connected levers for interconnecting said shaft and drag link, a uid pressure operated power means operatively connected with one of said levers, and a stationary stub shaft for mounting one end of both of said levers, said end of said vone lever being rotatably mounted on said stub shaft and said end of the other lever having limited movement with respect to the stub shaft for controlling said power means.

8. In a power steering apparatus for motor vehicles having a manuallyv operable steering shaft, a power operated steering arm, a stationary stub shaft, and a lever pivotally connected to both said steering shaft and said arm at points spaced along the length of said lever, the latter having a lost motion connection with said stub shaft, for controlling the application of power to said power operated steering arm.

WILERED A. EATON. STEPHEN voaEcH.

` I 4DlStCl-.AJNIER l,938,745.-Wilfred A. Eaton and Stephen Voreclt, Pittsburgh, Pa. STEERING Hereby enter this disclaimer to claim in the following words, to wit:

Disclaimer filed June 22,

stinghouse Automotive Air Brake Company.

3 of the aforesaid Letters Patent which is In a power steering mechanism for the dirigible'wheels of a motor vehicle, a Y manually operable steering member, alevercon'nected with said member and adapted to be oscillated thereby,

a power operated steering arm connected to the dirigible wheels of the vehicle, a fluid pressure power means operatively connected with said steering arm, valve means n for controlling said power means, said valve means comprisinga valve control lever pivotally and means for'controlling mounted on said steering arm, a connection between said valve control'lever and said first-named lever independent of said pivotal mounting, control lever and said valve means.

{Oicz'al Gazette July/24,1934] and a connection between one end of said valve 

